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White Space: No Answers This Summer

The FCC Office of Engineering and Technology has wrapped up its most recently announced batch of tests, with wireless mic tests at an NFL game Saturday and at a theatrical venue yet to be arranged.

But don’t expect fresh OET data or a notice of proposed rulemaking right away.

“I’m not sure all the testing will be done before the end of the summer,” FCC Chairman Kevin Martin said in a conference call with reporters Aug. 4. The tests are aimed to provide data to the commission as it begins making rules on potential devices operating in the unused DTV channels known as white spaces. Broadcasters fear such devices could interfere with DTV signals and derail the digital transition.

According to Steve Sharkey, Motorola senior director for regulatory and spectrum policy, the tests have proven the effectiveness of its geolocation database technology in helping identify channels used by DTV. Motorola is the only company that has submitted a device using that technology to avoid interference.

He said the geolocation database proved reliable. The geolocation database—in addition to adding speed by not having to scan channels already known to be occupied—makes the device more flexible and intelligent by giving it additional, and updatable information on the difficult task of detecting and evaluating the very weak signals, he said.

Google has also supported the geolocation concept.

The field testing is finished for Motorola. The company is not participating in the tests to sense wireless mic use, because it plans to use other means to protect wireless mic users—geolocation data, and beacons used by the incumbents. The company plans to submit a beacon device to the FCC soon; some wireless mic users had argued that no such beacons yet existed.

Sensing wireless mics is very difficult and creates the danger of false positives, Sharkey said.

Sharkey said there’s still plenty the device makers can do to their gear to respond to future direction from the FCC. So far, the FCC lab and field tests have provided plenty of data and given a sense of how such technologies would operate in a real-world setting.

Motorola has proposed a two-level white space regime, with different interference protection requirements for different levels of device power.

“This is some of the most comprehensive testing they’ve done,” Sharkey said. “There’ll be plenty of data and information for us to all sort through.”